This invention relates generally to tractor-mounted tools or implements for removing unwanted buried tree stumps, and more particularly to tree stump removers having articulating members arranged to provide a mechanical advantage in removing buried tree stumps and the like from the ground.
A number of mechanisms have been invented to remove partially buried and completely buried objects from the ground. Some of the early designs included hand tools that operated completely by human power. For example, U.S. Pat. No. 41,287 to Flanagan discloses a grubbing machine that removes buried tree stumps by engaging that portion of the tree stump extending above the ground surface. This design, however, can properly function only if a tree stump is relatively small in diameter, and is extending above the ground a distance required for the machine to receive and grip the extended portion thereof. In addition, this design is limited by the pulling power of the person operating the tool.
Another early design, disclosed in U.S. Pat. No. 277,894 to Flynn, is a hand operated "Lifting-Jack and Spike and Stump Puller." Like the Flanagan invention, Flynn's device is limited to buried objects that have a portion thereof extending to or above the surface of the ground. Also, like Flanagan, its use is limited by the strength of the person operating the tool.
Similar to Flynn, the subsequent hand operated design disclosed in U.S. Pat. No. 4,356,644 to Pederson shares the same limitations of most hand operated tools, i.e., only small objects buried near to or extending above the ground surface can be removed or pulled from the earth, and the lifting capacity is limited by a person's strength .
Later designs started to take advantage of powered machinery such as tractors. To reduce human labor, tractors provided power to assist in the operation and transportation of tools or implements that remove buried objects. For example, U.S Pat. No. 2,618,871 to Craver illustrates a hydraulically operated stump lifter connected to the rear of a tractor. The Craver invention operates by hydraulically lifting a buried object vertically from the ground. This design, however, relies on a hydraulically operated mechanism that operates independent of the pulling power of the tractor to remove the buried object. Such devices are somewhat complicated to maintain and are expensive to purchase. In addition, only stumps of limited size can be lifted because of the stroke limitations of the hydraulic cylinder. Similar to Craver, U.S. Pat. No. 3,057,599 issued to Clatterbuck, shares some of the same limitations, e.g., its expensive, complicated to maintain, and a power source independent of the pulling power generated by tractor movement is required. Thus, like Craver, an independently powered mechanical device is required in addition to the tractor. Moreover, like Flynn and Flanagan, a portion of the buried object must extend above the ground surface to provide a gripping surface for the device to engage prior to the removing process. Also, because the tractor remains stationary during the removal process, the maximum size of buried object is limited by the maximum movement of its hydraulic, moving parts.
Later designs started to address the problem of removing buried objects that had no portion thereof disposed above the ground surface for a tool to grip. Included is U.S. Pat. No. 2,877,572 to Dyess, and U.S. Pat. No. 3,103,076 to Schultz. Both designs incorporate a member designed to operate below the ground surface to reach a buried object. The Dyess design removes buried objects by positioning a wedge shaped plate below the ground surface while employing a tractor to pull the object from the ground. This design, however, employs the unassisted power of the tractor to pull the buried object from the ground, i.e., the tractor's power is not enhanced by an implement designed to create a mechanical advantage. Thus, removal of a buried object is limited to the direct pulling power of the tractor.
Likewise, the Schultz design removes objects buried below the ground surface. However, to remove the buried object, it provides lifting power from a hydraulic mechanism connected to the tractor. Thus, like Clatterbuck and Craver, Schultz requires lifting power furnished independent from the tractor. Accordingly, there is the expense and complexity of an independent hydraulically operated device.
More recently, U.S. Pat. No. 4,356,644 to Harkness discloses a tractor mounted device that removes objects buried below the ground surface by a pivoting member that is partially braced against the ground, and is operated with the assistance of a double acting hydraulic cylinder. Thus, Harkness, like some prior devices cited above, relies on an independently powered hydraulic device to remove an object from the ground.
While such devices, cited above, all remove buried objects or partially buried objects from the ground, no presently available tool or implement provides a tractor mounted articulating structure that employs forward movement of a tractor to create a mechanical advantage to remove a buried object.
Accordingly, a need remains for a stump-puller that is simple, inexpensive, easy and safe to operate, and that is readily adapted to small tractors with limited pulling power to remove buried objects that may have little or no portion thereof extending above the ground.